Improvements in the field of dental implantology have given restorative dentists and their partially or wholly edentulous patients the increasing option to support new artificial teeth on artificial roots. Prominent among the artificial roots that have become available is the osseointegrated dental implant fixture; commonly, this fixture takes a cylindrical form which is implantable in the patient's jawbone and has an axially located internally-threaded bore for receiving an externally threaded bolt which is used to attach to the implant fixture an artificial tooth, or an intermediate component between the fixture and the tooth. In practice one or more such bolts may be used to attach one tooth to an artificial root. The artificial tooth itself is frequently built on, or includes in its structure, a component which is designed and intended for cooperation with such a bolt. Thus, threaded bolts are important subcomponents in the structures of artificial teeth in a dental restoration supported on a dental implant fixture or fixtures.
With experience has come the realization that the bolts used in such dental restorations may have certain critical properties. The implant fixtures and the components assembled on them are made of materials chosen for suitability in dental use; presently the metal titanium is the material of choice. The bolts may suitably but not necessarily be made of gold. These are not hard metals such as steel that are commonly used in industrial structures, yet the bolts must be tightened enough so that the restored dentition will not fail in use. Attention has been given to designing and making the implant fixtures and related components to a high degree of dimensional precision and repeatability to minimize the opportunity of components to rock against each other and the implant fixture and thereby bending the attaching bolts and eventually breaking them. And, more recently, attention has been given to tightening the bolts just enough so that they will hold all the assembled parts tightly together throughout the range of forces those parts will encounter in use, but not so much that the bolts will be stretched beyond their elastic limit and break. The small sizes in which these bolts are made, as low as 1/16th of an inch, and generally not more than 1/8th of an inch in diameter at the peaks of their threads, have made this a critical and burdensome problem. To respond to the problem some tool manufacturers have provided complicated machines for controlling the torque applied to the bolts during assembly of the teeth and components on dental implant fixtures. Such machines that are currently available employ cabinets enclosing complex electronic motor control circuitry, a motor-driven handpiece for holding and driving a screwdriver bit, and a long flexible cable connecting the handpiece to the cabinet. Along with all this gadjetry is a group of settable controls on the cabinet and a handbook telling the dentist how to operate and maintain the equipment, and, of course, a correspondingly-high price.